JPH05231490A - Rolling ball type differential reduction gear mechanism - Google Patents

Abstract

PURPOSE:To increase transmission torque by providing an eccentric shaft with a rolling ball sliding between a first movable plate provided with a guide groove of either one of an epicycloid and a hypocycloid, and a second movable plate provided with a guide groove of the other curve, and transmitting only the autorotating component to an output shaft from a movement regulating plate. CONSTITUTION:A first movable plate 4 is provided, at its surface, with a guide groove 15 of 10, wave number formed by an epicycloid, and a second movable plate 6 is provided, at its face opposed to the first movable plate 4, with a guide groove 16 of 12 wave number formed by hypocycloid. An eccentric shaft 8 is rotated by a motor, and when eccentric torque is transmitted to the second movable plate 6 by an eccentric part 8a, the guide groove 16 is displaced in contact with the guide groove 15 of the first movable plate 6 through a rolling ball 17 so as to be rotated around the eccentric part 8a. A rotating ball 20 thereby rolls in both annular grooves 18, 19 of the second movable plate 6 and a movement regulating plate 12, so that the eccentric torque of the second movable plate 6 is absorbed, and only the torque is transmitted to the regulating plate 12 to rotate an output shaft 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an increase in transmission torque in a rolling ball type differential reduction mechanism.

[0002]

2. Description of the Related Art As a reduction mechanism of this type, Japanese Patent Laid-Open No.
No. 7,795,3 proposes a differential speed reduction mechanism combining an epicycloid orbit, a hypocycloid orbit, and rolling balls. However, the above-mentioned conventional differential reduction mechanism has a drawback that a ball cage for stopping the loose movement of the ball is required and the transmission torque is small because each track is not in contact with both side surfaces of the ball. Further, in this type of reduction mechanism, a rectifying means for absorbing the revolution component and transmitting only the rotation component is indispensable in order to absorb the eccentricity between the orbits, but it is necessary to similarly increase the transmission torque capacity in this portion. is there.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling ball type differential reduction mechanism capable of increasing the transmission torque capacity of the entire rolling ball type differential reduction mechanism including the rectifying means.

[0004]

A rolling ball type differential reduction mechanism of the present invention is a rolling ball in which torque is transmitted from a first moving plate to a second moving plate via a plurality of balls. In the differential differential reduction mechanism, a casing having insertion openings facing both side walls, an input portion arranged in either one of the insertion openings and rotatably supported by the casing, and an input portion of the input portion in the casing. An eccentric shaft having an eccentric portion that rotates around an axis and an inner surface of one side wall of the casing, the surface of which has a semicircular cross section corresponding to the ball, of an epicycloidal curve or a hypocycloidal curve. A first moving plate provided with a guide groove along either one of the first moving plate and the first moving plate is disposed in the casing so as to face the first moving plate, and is rotatably supported by the eccentric portion. On the moving plate side surface, A guide groove is provided which has a semicircular cross section corresponding to the ball, and which follows either the epicycloid curve or the hypocycloid curve having a wave number difference of 2 with the guide groove of the first moving plate. The second moving plate and the guide grooves of the first and second moving plates are fitted into the respective grooves and slide along with the rotation of the eccentric shaft while contacting the groove walls on both sides. A rolling ball that divides the rotational movement of the first moving plate into a rotation component and an orbital component, and a second moving plate and the other side wall of the casing facing the second moving plate. And a guide plate provided on the side of the adjusting plate of the second moving plate, the adjusting plate having an output shaft rotatably supported by either one of the inserting ports and the other inserting port. An annular groove having a semicircular cross section with a diameter commensurate with the amount of eccentricity based on the groove, the second of the adjusting plate It is provided on the moving plate side and rotates while contacting the annular groove of the same shape as the annular groove, and the groove walls of both of these annular grooves, and absorbs the revolution component of the second moving plate and only the rotation component. Rectifying means having a rotating ball for transmitting to the rectifying plate.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes a casing, and insertion holes 2 and 3 are formed in the left side wall and the right side wall so as to face each other. Reference numeral 4 denotes a first moving plate fixed to the inner surface of the right side wall of the casing 1, which has an annular disk shape and has a through hole 5 in the center which communicates with the one insertion port 3. 6 is a second moving plate having the same shape as the first moving plate 4, which is the casing 1
Firstly, a through hole 7 is provided in the center so as to face the moving plate 4
Have. 8 is an eccentric shaft provided in the casing 1,
One end of the eccentric portion 8a, which is in a state of being inserted through the through hole 5 of the first moving plate 4, is supported by the through hole 7 of the second moving plate 6 via a bearing 9. The other end of the eccentric shaft 8 is supported by the insertion port 3 via the bearing 10, and the portion protruding from the insertion port 3 to the outside is used as the input unit 11. In this case, the amount of eccentricity of the eccentric shaft 8 is made to correspond to that of the guide groove described later. 12
Is a disc-shaped adjusting plate, which is arranged in the casing 1 so as to face the second moving plate 6 and is provided in the center with the output shaft supported by the other insertion port 2 via a bearing 13. 14 is attached.

On the surface of the first moving plate 4, the second moving plate 2
As shown in the figure, a guide groove 15 having a semicircular cross section is formed. The guide groove 15 is continuously formed on a predetermined pitch circle with 10 wave numbers by an epicycloidal curve having a waveform as shown in FIG. 3 (a). Further, on the surface of the second moving plate 6 facing the first moving plate 4, a guide groove 16 having a semicircular cross section as seen in FIG.
Are formed. The guide groove 16 is formed continuously on a pitch circle having the same size as described above with 12 wave numbers by a hypocycloid curve having a waveform as shown in FIG. 3 (b). Here, the epicycloidal curve and the hypocycloidal curve are curves drawn when a small-diameter circle is moved in a circumscribed state and an inscribed state to a circle having a predetermined diameter dimension, and the wave height length dimension thereof is shown in FIG. 3 (a). , (B), the amount of eccentricity is indicated by the symbol e.

Reference numeral 17 is, for example, a steel rolling ball,
These are numbers one more than the wave number of the guide groove 15, that is, 1
Only one is provided, and the guide grooves 15 and 16 of the first and second moving plates 4 and 6 are arranged at the intersecting positions (at equal intervals), and are guided as the second moving plate 6 rotates. Roll along the grooves 15, 16. The rolling balls 17 are fitted in the respective grooves of these two guide grooves 15 and 16 and contact the groove walls on both sides while being supported by the groove walls from both sides in the radial direction and rolling.

Reference numeral 18 denotes an annular groove having a semicircular cross section, which is formed in the second moving plate 6 on the side opposite to the guide groove 16 and is formed in the guide groove 1.
It has a diameter commensurate with the amount of eccentricity based on 5 and 16, and a plurality of them are provided in the circumferential direction. Reference numeral 19 denotes an annular groove similar to the above, which is formed in the adjusting plate 12 so as to correspond to the annular groove 18 of the second moving plate 6. These second moving plate 6 and adjusting plate 1
A rotating ball 20 is arranged in the second annular grooves 18 and 19 to form a rectifying means 30. Rotating ball 20
Fits into each of these annular grooves 18, 19 and rolls while contacting the groove walls on both sides, and rotates while being supported by the groove walls from both sides in the radial direction. The orbital component of the second moving plate 6 is absorbed and only the rotational component is absorbed by the adjusting plate 12.
Communicate to.

When the above configuration is applied to a transfer robot, an electric motor (not shown) is provided at the input portion of the eccentric shaft 8.
Are connected to the output shaft 14, and a transfer arm (not shown) is attached to the output shaft 14. Then, when the electric motor is driven, the eccentric shaft 8 rotates, and the eccentric rotation force is transmitted to the second moving plate 6 by the eccentric portion 8a. The second moving plate 6 which receives this eccentric rotational force is displaced with the guide groove 16 constantly contacting the guide groove 15 of the first moving plate 4 via the rolling balls 17 as shown in FIG. It rotates around the eccentric portion 8a of the shaft 8. The movement of the second moving plate 6 causes the rotating ball 20 to roll along the annular grooves 18 and 19 of the second moving plate 6 and the adjusting plate 12, thereby causing the eccentric rotation of the second moving plate 6. The force is absorbed and erased, and only the rotational force of the second moving plate 6 is transmitted to the rectifying plate 12 by the rotating ball 20 to rotate the output shaft 14 and move the arm.

In this case, one rotation amount of the eccentric shaft 8 corresponds to the amount by which the rolling ball 17 moves in the guide grooves 15 and 16 by the length dimension corresponding to two wave numbers. And the numerical value obtained by adding the number 2 to the wave number N of the guide groove of the first moving plate, that is, 2 / N + 2. In the above embodiment, the guide groove 1
Since the wave number N of 5 is 10, the reduction ratio is 2/10 + 2
= 1/6. Thus, while ensuring a relatively high reduction ratio, the first moving plate 4 and the second moving plate 6 only have to be arranged side by side so as to be opposed to each other, so that the thin plate is short in the left-right direction. The whole becomes smaller.

Further, since the first moving plate 4 and the second moving plate 6 are connected by the rolling balls 17 through the guide grooves 15 and 16, these first and second moving plates are connected. 4,
The play between 6 can be removed, and the rotation angle of the output shaft 14 can be set with high accuracy. In addition, the first moving plate 4 and the second moving plate 6 are inserted into the rolling balls 1 via the guide grooves 15 and 16.
Since it is securely connected by 7, the moving plates 4 and 6 are integrated and have high rigidity, while the rolling balls 17 are provided in close contact with the guide grooves 15 and 16 without rattling, so that backlash does not occur. Of course, such play is eliminated, and the meshing ratio is increased.

FIG. 5 shows a second embodiment of the present invention. In this second embodiment, the first moving plate 4 and the adjusting plate 12 in the first embodiment are arranged opposite to each other. There is. Therefore, the adjusting plate 25 is provided with a through hole 26 through which the eccentric shaft 8 is inserted, the second moving plate 27 is made non-perforated, and the output shaft 28 is connected to the center thereof. Even if it is configured as in the second embodiment, the same effect as in the first embodiment can be obtained. In each of the above-described embodiments, the same members are designated by the same reference numerals and only different portions are described.

[0013]

As described above, according to the present invention, the guide groove has a semicircular shape, and the rolling ball comes into contact with the groove wall of the guide groove and rolls. It is supported by the guide groove from both sides in the radial direction. As a result, the engagement ratio doubles as compared with the case where the guide groove has a large groove width and the balls make contact with only one surface of the guide groove to roll, and a large torque can be transmitted. Further, in the present invention, the rectifying means is also a combination of annular grooves having a semicircular cross section and a rotating ball fitted in each of these grooves, and compared with the case where the entire annular grooves are circular holes, 2 It has a double meshing ratio. As a result, a large torque capacity capable of transmitting the large torque transmitted by the ball with a compact size can be achieved.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the entire first embodiment of the present invention.

FIG. 3 is an explanatory view of the shape of the guide groove of the first embodiment of the present invention.

FIG. 4 is an explanatory view of the operation of the first embodiment of the present invention.

FIG. 5 is an overall vertical cross-sectional view of a second embodiment of the present invention with a case removed.

[Explanation of symbols]

 4 1st moving plate 6, 27 2nd moving plate 15, 16 Guide groove 17 Rolling ball 20 Rotating ball 30 Straightening means

Claims (1)

[Claims] 1. A rolling ball type differential reduction mechanism in which torque is transmitted from a first moving plate to a second moving plate via a plurality of balls, and a casing having insertion openings facing both side walls, An eccentric shaft provided at any one of the insertion ports and rotatably supported by the casing, and an eccentric shaft having an eccentric portion that rotates around the axis of the input unit in the casing; It is provided on the inner surface of one side wall of the
A first moving plate having a semicircular cross section corresponding to the ball and provided with a guide groove along one of the epicycloid curve or the hypocycloid curve, and the first moving plate in the casing. While being arranged facing each other, rotatably supported by the eccentric portion, the first moving plate side surface has a semicircular cross section corresponding to the ball,
A second moving plate provided with a guide groove along the other of the epicycloid curve or the hypocycloid curve having a wave number difference of 2 with the guide groove of the first moving plate; Fitting in each groove in each guide groove of the second moving plate and sliding along with the rotation of the eccentric shaft while contacting the groove walls on both sides, the rotational movement of the first moving plate,
A rolling ball that is divided into a rotation component and an orbital component, and is disposed between the second moving plate and the other side wall of the casing, facing the second moving plate, and either of the insertion holes. A rectifying plate having an output shaft rotatably supported in the other insertion port, and a circle provided on the rectifying plate side face of the second moving plate and having a diameter corresponding to the eccentric amount based on the two guide grooves. An annular groove having a semicircular cross-section, an annular groove provided on the second moving plate side of the rectifying plate, and having the same shape as the annular groove, and rotating while contacting the groove walls of both of these annular grooves. A rolling ball type differential reduction mechanism comprising: a rectifying unit having a rotating ball that absorbs an orbital component of the second moving plate and transmits only a rotation component to the rectifying plate.